1. Field of the Invention
This invention relates generally to an oral composition which when applied onto the surface of teeth acts to whiten teeth and more particularly to an oral composition for whitening teeth that is more effective than existing products available to the consumer.
2. The Prior Art
A tooth is comprised of an inner dentin layer and an outer hard enamel layer that is the protective layer of the tooth. The enamel layer of a tooth is naturally an opaque white or slightly off-white color. It is this enamel layer that can become stained or discolored. The enamel layer of a tooth is composed of hydroxyapatite mineral crystals that create a somewhat porous surface. It is believed that this porous nature of the enamel layer is what allows staining agents and discoloring substances to permeate the enamel and discolor the tooth.
Many substances that a person confronts or comes in contact with on a daily basis can "stain" or reduce the "whiteness" of one's teeth. In particular, the foods, tobacco products and fluids such as tea and coffee that one consumes tend to stain one's teeth. These products or substances tend to accumulate on the enamel layer of the tooth and form a pellicle film over the teeth. These staining and discoloring substances can then permeate the enamel layer. This problem occurs gradually over many years, but imparts a noticeable discoloration of the enamel of one's teeth.
There are available in the marketplace oral compositions for home use which contain 1-3% by weight concentrations of a peroxygen compound such as hydrogen peroxide and when applied on the teeth effect whitening of stains. However, these compositions are considered to have a slow bleaching effect.
Illustrative of oral compositions containing peroxygen compounds for whitening teeth include U.S. Pat. Nos. 5,302,374, 5,279,816, 4,988,450; 4,980,152, 4,839,156, 4,405,599, 3,988433 and 3,657,417.
U.S. Pat. No. 5,279,816 discloses an oral composition for whitening teeth containing peracetic acid dissolved or suspended in a vehicle. U.S. Pat. No. 5,302,374 discloses generating peracetic acid within a dentifrice vehicle by combining water, acetylsalicylic acid and a water soluble alkali metal percarbonate.
U.S. Pat. Nos. 4,988,450 and 3,657,417 disclose formulating oxygen liberating compositions for the whitening of teeth utilizing anhydrous pastes or gels.
U.S. Pat. No. 4,980,152 discloses an aqueous oral gel composition comprising about 0.5 to about 10% by weight urea peroxide and 0.01 to 2% by weight of a fluoride providing compound.
U.S. Pat. No. 4,839,156 discloses a water containing a hydrogen peroxide-Pluronic thickened oral gel composition.
U.S. Pat. No. 4,405,599 discloses a toothpaste containing a combination of calcium peroxide and sodium perborate oxidizing agents, dicalcium phosphate, calcium carbonate and magnesium carbonate cleaning agents, sorbitol humectant, cornstarch and cellulose gum thickening agents, and an anionic detergent.
U.S. Pat. No. 3,988,433 discloses oral compositions containing peroxyacids and alkyl diperoxy acids having alkylene groups containing 5-11 carbon atoms which remove stain from teeth.
In those applications where oral compositions are designed for home use whitening of teeth, it is essential that the peroxide generating components react quickly since the user will normally wish to limit the time in which the whitening composition is in contact with the teeth. To accomplish this, applicant has recognized the desirability of accelerating the breakdown of peroxygen compounds and the release of active oxygen within the oral cavity to effect a more rapid whitening of the teeth.